The narrow pulse cut is based on logged NCD signal and is coded as a SNOMAN hard-wired cut "flt_narrow_pulse_cut.for". The parameter for this cut can be found in "filter_flth.dat" :
*DO FLTH 34 -i(30I -I) #. FLTH: Narrow Pulse Cut #. 19750101 0 20380517 03331900 6*0 #. Standard Database Header 19750101 0 20380517 03331900 16*0 #. 250 #. threshold on width of pulse
A event is tagged as a narrow pulse if the FWHM (full width half maximum) is less than 250 (or the first parameter in FLTH). A narrow pulse can be caused by micro discharge or so-called endcap alpha.
To use this cut, one can put a call flt($narrow_pulse_cut) in the programmable event loop. The cut returns "tree" if the event is a good event.